1. Field of the Invention
The present invention relates to a stator structure of a variable reluctance resolver, and more particularly concerns a stator structure of a variable reluctance resolver having excellent waterproofing, oil-proofing, vibration resisting and shock resisting features.
2. Description of the Related Art
In a resolver for various uses such as detection of rotating position, there is provided a variable reluctance resolver having a plurality of magnetic poles projecting from a circular yoke member, and a rotor in a stator in which stator windings are wound around the magnetic poles.
In the stator magnetic pole of the variable reluctance resolver, a plurality of circular yoke members formed by stamping out a soft iron plate with a press die are laminated to form a stator core. In the structure of the stator, stator windings wound around a plurality of magnetic poles of the stator core are subjected to potting, on which a protective cover is fixed with an adhesive, or a stator is vertically sandwiched with a cover mechanically. In addition as another structure, a member made of an insulator (stator magnetic-pole assembly) for winding a coil around the stator core is disposed in a manner so as to surround magnetic-pole teeth of the stator core. In order to ensure insulation between the winding coil and the stator magnetic-pole assembly covering the stator magnetic poles, an insulator made of an insulating material such as a resin is separately formed, and which is inserted in the coil winding sections of the stator magnetic-pole assembly. Alternatively, an insulating coating is directly sprayed onto the stator magnetic-pole assembly or chemical treatment is applied to form a thin insulating film over the entire surface without inside surface of the poles.
However, in the structure in which the protective cover is fixed with the adhesive, it may be disengaged due to change in temperature, vibration, or shock. In addition, since a claw section of the protective cover made of the insulating material such as the resin is inserted in a slot section in which the coil of the stator magnetic-pole assembly is wound, a coating of the coil is damaged to cause an insulation failure of the coil thereby deteriorating reliability of the variable reluctance resolver. Although such protection structure is effective for a mechanical damage, it is difficult to resist severe environment such as water proof, vibration, and shock.
Furthermore, in assembling a small variable reluctance resolver, there is no space for pressurizing and fastening the entire circular yoke member with eyelet, the yoke member being stamped out with the press die, and no pressure-fastening force is applied to a tip peripheral rim of the fixed magnetic-pole tooth. Therefore, problems occur in that a gap is formed between the laminated yoke members of the stator of the variable reluctance resolver so assembled so that rust generates at the inner portion of the laminated bodies during operation for a long period, and also when the stator is magnetized or the rotor is rotated, the laminated bodies are vibrated to generate a noise.
In order to solve the above problems, for example, a method of Japanese Unexamined Patent Application Publication No. 10-322944 is disclosed, in which a synthetic resin layer is formed on a surface of the stator magnetic-pole assembly, and surrounds with the stator, and subsequently the windings are wound in order to solve the problems. However, problems remain in waterproofing, oil proofing, vibration resisting, and shock resisting.
Accordingly, it is an object of the present invention to provide a stator structure of a variable reluctance resolver having excellent water proofing, oil proofing, vibration resisting, and impact resisting features.
In order to achieve the above objects, in a stator structure of a variable reluctance resolver according to the present invention, comprises: a stator core having a torus shape, in which a plurality of fixed magnetic-poles each having a fixed magnetic-pole tooth project toward the center of a circular yoke member, and a plurality of planar bodies are laminated; a first stator magnetic-pole assembly including coil winding sections having the same shape and number as the fixed magnetic poles each having the fixed magnetic-pole tooth of the stator core, and a part mounting section for extracting stator windings; and a second stator magnetic-pole assembly including coil winding sections having the same shape and number as the fixed magnetic poles each having the fixed magnetic-pole tooth of the stator core, and including no part mounting section, wherein the stator core is sandwiched by the first stator magnetic-pole assembly and the second stator magnetic-pole assembly from the both sides in a manner such that the fixed magnetic poles and the coil winding sections overlap to form a stator assembly; and wherein the stator assembly having the stator windings wound around the coil winding sections thereof is surrounded by a synthetic resin, wherein the synthetic resin surrounds the first stator magnetic-pole assembly and the second stator magnetic-pole assembly at the stator winding sections in a manner such that a surface at which the fixed magnetic-pole teeth of the stator core face a rotor is exposed, and a surface of the synthetic resin forms the same circumferential surface as the surface at which the fixed magnetic-pole teeth face the rotor.
In the stator structure of the variable reluctance resolver, preferably, the first stator magnetic-pole assembly and the second stator magnetic-pole assembly include uneven sections for increasing a creeping distance at a contact section relative to the synthetic resin.
In the stator structure of the variable reluctance resolver, preferably, the uneven section for increasing the creeping distance is provided at the surface that comes into contact with the synthetic resin on overhung section for retaining the stator winding wound around the coil winding section of the stator assembly.
In the stator structure of the variable reluctance resolver, preferably, the circular stator core has a plurality of through holes along the outermost periphery of the surrounding synthetic resin.
In the stator structure of the variable reluctance resolver, preferably, the part mounting section provided for the first stator magnetic-pole assembly, and the circular stator core have a plurality of through holes, respectively, and the through holes are arranged at positions where the through holes of the part mounting sections correspond to those of the circular stator core.
In the stator structure of the variable reluctance resolver, preferably, the synthetic resin, the first stator magnetic-pole assembly, and the second stator magnetic-pole assembly have almost the same thermal expansion coefficient.